On December 27, 1999, at 1800 central standard time, a Cessna 172L airplane, N172GT, owned and operated by Southernaire Carrier, Inc., of Tupelo, Mississippi, was substantially damaged when it collided with a seawall and hangar during engine start at the Lakefront Airport, near New Orleans, Louisiana. The private pilot was not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the proposed 14 Code of Federal Regulations Part 91 personal cross-country flight. The pilot reported to the NTSB investigator-in-charge that while attempting to start the airplane's engine, the starter's bendix drive gear did not engage the starter ring gear. He turned off the ignition, took out the key and put it in his pocket, pulled the throttle to the idle position, set the parking brake and got out of the airplane. He chocked the airplane and then slowly rotated the propeller until he felt one piston "move to top center." He then got back in the airplane and attempted another start; however, the starter's bendix drive gear still did not engage the starter ring gear. Once again he turned off the ignition, took out the key and put it in his pocket, pulled the throttle to the idle position, and got out of the airplane. He was not sure if he pulled the mixture to the off position, but he thought he did. As he manually rotated the propeller, the engine started. The airplane jumped the chocks and began traveling forward with nobody on board. According to the FAA inspector who went to the accident site, the airplane traveled about 150-200 feet until it impacted a seawall and a hangar. An examination of the airplane revealed that the engine was "shoved back" into the firewall, and the engine mounts were broken. The right wing's strut and spar were bent, and the left wing tip was damaged. During an examination of the magnetos and starter system, an intermittent short was found in the starter switch, which allowed the magnetos to remain ungrounded or "hot" with the switch in the "off" position.